Fine structure of the main sequence of NGC 2516 scrutinized with Gaia and ASteCA

GIORGI, E.; CRUZADO, A.; PERA, M.S.; VÁZQUEZ, R.A.; PERREN, G.; NAVONE, H.D.

Rosario

Congreso; 62° Reunión Anual de la Asociación Argentina de Astronomía; 2020

Asociación Argentina de Astronomía

The fine structure of the open cluster NGC 2516 is investigated down to G=19 mag thanks to the unprecedented precision of the GaiaDR2 (Gaia second data release). This is an extended and relatively young open cluster subtending over two degrees in the sky, situated at just a few hundred parsecs (< 400 pc) from the Sun. The total surface coverage with usual photometric technics meanstremendous time consumption at the risk of losing cluster members around some bright stars.We collected Gaia DR2 data (G magnitude and BP-RP color index, together with proper motions and parallaxes) for more than 400000 stars in a region of 6 degrees on a side, and applied a variation of the UPMASK algorithm, which we call pyUPMASK. pyUPMASK is a probability membership estimation algorithm designed by our group that considerably out-performs UPMASK. Once the membershipprocess is finished, Gaia data for the most probable members was cross-matched with available UBVI data. Finally, we run our ASteCA code to obtain the fundamental cluster parameters. Our data analysis process revealed a clear star sequence of binary star well detached from a tight main sequence, in agreement with what is expected in a not so evolved open cluster.